A casino is an establishment for certain types of gambling. It may be combined with hotels, restaurants, retail shops or other tourist attractions. In modern usage, the term may also refer to an online casino.

Gambling almost certainly predates recorded history, with primitive protodice (cut knuckle bones) and carved six-sided dice found in the oldest archaeological sites. The casino as a place to find a variety of ways to gamble under one roof did not develop until the 16th century, when gambling mania swept Europe. At that time, wealthy Italian aristocrats held private parties at their residences known as ridotti which were technically illegal but rarely bothered by legal authorities.

Casinos make money by reducing the odds of winning for their patrons. The advantage can be very small, lower than two percent, but the millions of bets placed earn casinos enough to construct elaborate hotels, fountains, giant pyramids and towers and to sponsor sports teams, celebrities and popular artists. This income is called the vig or rake, and it varies from game to game.

Security is a major concern for casino managers and operators. Casino employees watch the games and the players closely to prevent cheating, including palming, marking, and switching cards or dice. Dealers are highly trained to spot sleight of hand, and table games have pit bosses and manager to ensure that players are not taking unfair advantage of the casino. Casinos also offer comps to their best customers, often giving them free rooms, meals and tickets to shows.